High Strength Vitamin D

Recently my specialist did a vitamin D test that no one has done over the years and found I also have low vitamin D. I am taking Dr's Best 1000ui (which is a brand from America) Is anyone else taking this? as UK only do 10ui which i wonder why that is?!
I have been feeling nauceous and been getting a lot of acid burning in the back of my throat like indegestion.
Just wondered if anyone else had this experience?

Thank you for your reply. Did you get yours supplied by your Doctor? are you in the UK? I had to get mine on the internet as UK does only 10ui. They are gel capsules and have olive oil,gelatin,vegetable glycerin,purified water. That is all that is in them and the vitamin D derived from lanolin a component of sheeps wool. Was wondering if it was the lanolin?!